Ulnar-Mammary Syndrome

Abstract

Ulnar-mammary syndrome (UMS) is characterized by ulnar ray defects, delayed growth and onset of puberty, and hypoplasia of the breasts/nipples and apocrine glands. Postaxial limb defects range from shortening of digit V to absence of digits III–V and ulna with radial shortening. The most severe cases show complete absence of the radius/ulna and hand. Further features include fusion of the interphalangeal joints with hypoplastic/absent flexion creases, ventral duplication of the nail of digit V, clinodactyly of digit V, postaxial polydactyly, and wide space between digits IV and V. Generally, the feet are not affected, but toes IV and V can be short. Apocrine abnormalities in UMS include diminished or absent axillary hair, reduced or absent perspiration, hypoplasia/aplasia of the breasts, supernumerary nipples as well as hypoplasia of the nipples, and hypopigmentation and/or hypoplasia of the areola. Hypogonadism and delayed puberty are seen in males. Dental abnormalities include ectopic, hypoplastic, and absent canine teeth. Genital anomalies, such as micropenis, shawl scrotum, and imperforate hymen are further features. A wide range of phenotypic expression exists in UMS. Up to a third of mutation carriers have nearly normal limbs and show only a few minor anomalies. Affected individuals may have a similar facial appearance with a broad nasal tip, broad jaw, prominent chin, and tongue frenulum.